I’ve been hearing for years about leaf lard, the sheet of creamy fat that protects the kidneys of a hog. I was curious to use it in pastry but never motivated enough to special order it or arrive early to the Greenmarket. Yesterday, during my first visit to Marlow & Daughters in Williamsburg, I was greeted by pounds and pounds of it, both raw and rendered, in the freezer case.

Marlow & Daughters is kind of a dream come true. It’s the sort of store I’d open if I had an entrepreneurial spirit. It had all the stuff I like, from Rancho Gordo beans to Bay’s English Muffins, house-made sausage to beautiful, luscious roast beef. They had a small pile of perfect lemons for 50 cents each. The service was friendly and knowledgeable, and I felt good spending money there.

Back to the lard. I asked one of the gentlemen behind the counter about grinding it for rendering, and instead of forcing the ice block of fat through the grinder, he found some fresh in the back. He weighed out two pounds and sold it to me for $10.

I came home, ready to make an onion tart, but first I engaged in some serious googling to figure out how to render the huge block of fat in my fridge. The most useful resource turned out to be Flying Pigs Farm. I didn’t want to screw it up, and they offered precise instructions with temperatures to watch for.

Start with the ground fat in a heavy roasting pan. Some directions tell you to add water to get the process started and keep the fat from scorching in the oven, but I don’t see why you’d need to do this. I feel the same way about caramel; adding water just makes it take longer.

Break it up with a wooden spoon, and stick it into a 300ºF oven for an hour or more, stirring frequently, until the fat registers 255ºF on an instant-read thermometer. You’ll know it’s done when the cracklings have sunk to the bottom. It will look something like this, and it will smell like a diner:

Let the fat cool for a few minutes, and then ladle it through a cheesecloth-lined strainer. Scoop out the cracklings and save them for your next salad or soup.

You’ll be left with a bowl of beautiful, clear fat.

I transferred mine to a medium loaf pan and cooled it over ice. You’ll want to do this rather quickly because it hardens as it cools, and it gets messy transferring it from one vessel to another. Put it where you intend to keep it, in other words. In less than 30 minutes it will become a hard block of snow-white fat, which will keep for a long time in the fridge and for years in the freezer.

I thought an Alice Waters onion tart would be a good trial run for the lard. I used my school proportions of flour and fat: 200 grams flour to 100 grams butter. I replaced 3/4 of the butter with lard, and this worked perfectly well. The crust took a while to brown, but even after an hour in the oven, it was flaky, tender, and flavorful. It didn’t smell or taste of pig.

If anyone has good uses for lard to suggest, please leave them in the comments. I intend to buy Jennifer McLagan’s book today; I’ll report back sometime in the next three months on any great successes.